85 150 stl,hard start and spits and sputters at wot

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madogjack

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Aug 3, 2011
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I have a stratos 175 with an 85 evinrude xp150 stl and this thing is driving me crazy. I rebuilt the carbs and every since it is hard to start and when I do have it started it will only run at a slow speed without boging, sputtering and some of the time it will die, after I mess with it for a while it with smooth out and run like a new engine, how ever, when I stop and fish for a while this will start all over and I have the same problem once more. I sure hope some one knows what to do ,I will appreciate any and all suggestions.
 
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boobie

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Re: 85 150 stl,hard start and spits and sputters at wot

Start with a compression test. Then a spark test on an open air gap spark tester set at 7/16 ". You still may have carb probs.
 
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emdsapmgr

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11,551
Re: 85 150 stl,hard start and spits and sputters at wot

You mention slow speed/idle problems. How does the engine run at WOT? If it runs fine at WOT, it's unlikely a spark or fuel delivery issue. Could be debris/dried fuel in the idle passages of the carbs.
 
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madogjack

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Re: 85 150 stl,hard start and spits and sputters at wot

When I took the engine out of storage I checked the compression and it is 120 to123 on all cylinders, I have checked the carbs and they seem to be OK. what puzzel's me is the fact after fooling with it at low speed (running the throttle up and down) it will work out the problem and take off and run wide open. it is just when I start it I can't give it the throttle with out it shutting down.
 
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emdsapmgr

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Re: 85 150 stl,hard start and spits and sputters at wot

When you idle the engine, the carb butterflys are closed. Fuel is delievered via special dedicated idle passages in the upper carb body. If they are restricted at all, the engine will struggle at idle. As soon as you crack the throttle even just a little, the carb will start to supply fuel from other jets (mid and high) and the engine may run fine. You may find the engine will run great at every rpm, except idle.
 
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madogjack

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Re: 85 150 stl,hard start and spits and sputters at wot

IT WILL IDLE FINE @ 750 rpmS ONLY WHEN I ATTEMPT TO SPEED UP WILL I have a problem, it will start to increase speed then bog down, speed up again and then just as it gets out of the hole it will shut down, allmost dying sometimes and it will do this several times. You may be right ,I may still have a carb problem, but I can't figure out why it will smooth out after it has run for a while. I appreciate every one's input I now have things I can check. My fishing partner solved the hard start issue, I was not holding the primer in long enough duh". Thanks again
 
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emdsapmgr

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Messages
11,551
Re: 85 150 stl,hard start and spits and sputters at wot

Thanks for the clarification on the issue. You may have a weak fuel pump. You can try a test. Next time out, when it starts to bog, have someone constantly prime the fuel hose bulb. This will force extra fuel into the carb bowls. If it runs fine at all rpm's as long as you keep priming the bulb, you may have weak pump. It may pump some fuel, but not enough to sustain full throttle operation.
 
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madogjack

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Aug 3, 2011
Messages
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Re: 85 150 stl,hard start and spits and sputters at wot

Thanks a lot I,ll try that tomorrow, that was one thing I had not thought of.
 
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